Question

1. Compare and contrast the role of promoters versus enhancers in controlling gene expression by answering the following questions.

   1. Are they cis- or trans- acting components of the regulatory machinery? Explain why this label applies to each?

   2. Where are they located relative to the transcription start site (TSS) of a gene?

   3. What kinds of transcription factors (TFs) does each element bind, and what are the particular TFs’ role in gene expression?

Answer 1

1. Promoter are the region in the DNA where the transcription start and enhancer is the region of DNA where different proteins binds to increase the transcription of gene. Promoter is situated close to the gene that is being transcribed and hence are trans-acting  where's enhancer may or may not be situated close to gene being transcribed and hence cis-acting .

2. Promoter are located upstream of the gene sequencnce that is going to transcribe whereas enhancers of the gene sequence could be located either on the upstream and downstream of the gene being transcribed.

3. Transcriptions factor that bind to the promoter region are a part of transcriptions initiation complex whereas  transcriptions factor bind to the enhancer region only increase the rate of transcription, that are not a part of transcriptions initiation complex .